Draw a node of an outline structure. You can draw other nodes inside it and
connecting lines will appear.

node { config | label = "Claim" }

type NodeLayout msg
= NodeLayout (Html msg)

A wrapper for a node rendered into Html. This type exists to prevent us
from accidentally wrapping a node in a container element before passing it as a
child to another node or segment. Such wrapping would break some of our
styling, which assumes nodes of the same level are sibblings in the Html tree.